This invention relates to a digital comparator, and more particularly to a digital comparator which is used for forming timing signals.
A digital comparator for forming timing signals is required in, for example, an automatic exposure control system of a camera.
In the automatic exposure control system of a camera in which a control portion of a shutter is constructed of an electronic circuit, a CR time constant circuit consisting of a resistor and a capacitor is usually employed so as to continuously vary the shutter speed. Since, however, the system employing the CR time constant circuit is inferior in accuracy, it is requested to digitalize the shutter control circuit. In this case, a digital comparator becomes necessary which compares a timing pulse and a set digital value to obtain a predetermined shutter speed.
Heretofore, the digital comparator has been constructed of exclusive OR circuits, which has resulted in the disadvantage of a complicated circuit arrangement. It has accordingly been difficult to put timing signal generators of the shutter control circuit etc. into digital circuits.